The present invention relates to a defect inspection device and defect inspection method for inspecting semiconductor wafers and liquid-crystal substrates.
When LSI or liquid-crystal substrates are manufactured, repetitive patterns are formed on objects to be worked (e.g., semiconductor wafers). During the manufacture of the LSI or liquid-crystal substrates, if foreign matter sticks to or defects occur on the surface of the work piece, this causes, for example, improper insulation of wiring, short circuiting, or other unwanted events. As finer-structured circuit patterns are formed in such manufacturing processes, non-defectives that are the patterns formed on work pieces are becoming difficult to discriminate from fine foreign matter or defects. The defects here are particles sticking to the sample that is the object to be inspected, crystal-originated particles (COPs), other crystal defects, scratches due to polishing, and other surface defects.
Patent Document 1 (JP-A-2007-273513) discloses a dark field defect inspection system and method in which, after a sample to be inspected has been irradiated with light admitted in an oblique direction, a diffraction pattern of the light diffracted from a repetitive circuit pattern present on the sample is blocked by a spatial filter previously set to assume a certain state. The inspection method includes the steps of, prior to defect inspection, using as a correction test object for re-setting the spatial filter the light diffracted from part of repetitive circuit patterns on the object to-be-inspected, measuring the amount of diffracted light that the spatial filter has reduced, comparing the amount of diffracted light with a threshold level, and re-setting the spatial filter so that the amount of diffracted light decreases to or below the threshold level.
Patent Document 2 (JP-A-2008-116405) discloses a dark field defect inspection system and method in which, after a sample to be inspected has been irradiated with light admitted in an oblique direction, a diffraction pattern of the light diffracted from a repetitive circuit pattern present on the sample is blocked by a spatial filter. The inspection method includes the step of observing the diffraction pattern, the step of recognizing the observed diffraction pattern by image processing, and the step of creating a spatial filter shape that is to block the recognized diffraction pattern.